1. Field of the Invention
The present invention relates to a method of controlling a fuel cell vehicle and a method of a DC/DC converter apparatus, the fuel cell vehicle and the DC/DC converter apparatus including a DC/DC converter having a plurality of switching devices connected in parallel between two electric power devices (e.g. a fuel cell and a power storage device), and a controller for controlling voltage conversion performed by the DC/DC converter. More particularly, the present invention relates to a method of controlling a fuel cell vehicle and a method of controlling a DC/DC converter apparatus, in which the controller can execute direct couple control that directly couples the two electric power devices without voltage conversion being performed by the DC/DC converter.
2. Description of the Related Art
There has been known a DC/DC converter apparatus which performs voltage-increasing and voltage-decreasing processes using a plurality of switching devices (Japanese Laid-Open Patent Publication No. 2004-357388). The DC/DC converter apparatus disclosed in Japanese Laid-Open Patent Publication No. 2004-357388 includes a plurality of phase arms. Each phase arm is a combination of one upper switching device and one lower switching device, and is operable to perform both voltage-increasing and voltage-decreasing processes. The phase arms are operated in such a manner that their operation cycles are phase-shifted relative to one another to perform the voltage-increasing and voltage-decreasing processes (see the abstract of Japanese Laid-Open Patent Publication No. 2004-357388).
U.S. Patent Application Publication No. 2006/0012340 A1 discloses a technique for reducing electric power loss caused by operating a switching device when a fuel cell and a power storage device are directly coupled via a DC/DC converter. In U.S. Patent Application Publication, No. 2006/0012340 A1, the DC/DC converter apparatus is incorporated in a fuel cell vehicle.
As described above, techniques for increasing/decreasing voltage using a plurality of switching devices, and for directly coupling a fuel cell and a power storage device are known. However, a configuration which is capable of directly coupling a fuel cell with a power storage device using a DC/DC converter apparatus having a plurality of switching devices is not yet known, and hence, a suitable method for controlling such a configuration has not yet been studied.